docs: def extract(self, name):
          """
          Get the object corresponding to name, or None.
          For use with imputil ArchiveImporter, object is a python code object.
          'name' is the name as specified in an 'import name'.
          'import a.b' will become:
          extract('a') (return None because 'a' is not a code object)
          extract('a.__init__') (return a code object)
          extract('a.b') (return a code object)
          Default implementation:
            self.toc is a dict
            self.toc[name] is pos
            self.lib has the code object marshal-ed at pos
          """
          ispkg, pos = self.toc.get(name, (0, None))
          if pos is None:
              return None
          self.lib.seek(self.start + pos)
          return ispkg, marshal.load(self.lib)